Clean up code. Reorganize files. Port stuff from other branches. + more

This turns the project into a monorepo using pnpm workspaces,
dramatically simplifying the build process. It also fixes a lot of bugs
and just generally makes the codebase a lot cleaner.

example-app/config.toml

@@ -1,7 +1,7 @@
 strategy = "target_number"
 
 [leading_zeroes]
-difficulty = 4
+difficulty = 2
 
 [target_number]
-max_number = 10000
+max_number = 192